"Original drums used to be made of of average metal and were...

"Original drums used to be made of of average metal and were over specified to hell as no one ever worried about weight and weight meant that you had more metal to remachine them a few times in their life. "

The over specification sometimes becomes useful remember following a lightly loaded flat bed rig down into Sacramento off the Sierras and still having the brakes overheating(smoking) while only doing 15mph due to the long steep gradient the large thick drums act as a heat sink up to a point then the temperature gets too hot .
But yes you are correct on the transfer of tech from Aerospace industry , ie hydraulics on plane landing gear seemed to have occurred widespread about 20 years earlier than it being applied to the earth moving industry .

As to being on the blower I use to sell on my own in excess of US$6M a year in light trucks and SUVs (in Sacramento ) at a dealership these guys have got a bit of catching up to do on me .
I use to spend an hour a day doing follow up calls and another hour doing emails until the potential buyers were so frustrated they either told me to get lost or bought .